There is another possibility, you could bypass uphauling and go straight to water starting.
At 80l and 55cm wide that board will be very hard to uphaul. I've been windsurfing since 1985, and I'm struggling to up haul my 90l 53cm board, unless the water is very calm, and I'm the same weight as you.
But water starting it is a doddle.
Start of on the beach with the board across the wind. Try and put your weight on the sail, by hanging onto the boom.
First thing to learn here, is that hands and feet are back and front NOT left and right!
So the front hand holds the rig, the back hand controls the power, if there's too much power let go with the back hand.
So this is a delicate balancing operation, adjusting the power in the sail to counterbalance your weight.
With your weight and a 5m2 sail you could start this in about 10knots, but you won't be able to put a lot of your weight on the rig. If you have the sail rigged correctly, you should be able to work up to around 20knots, then you'll be able to put virtually all your weight on the sail.
But as with learning anything in windsurfing, all ways do this in both directions!! Just because you've taught your body something in one direction doesn't mean you can do it in the other direction.
Once you think you can do this, the next thing to try, is lay down alongside the board, and try using the sail power to pull you to your feet.
Feel OK with that? OK, now you can put the board in the water, align it across the wind and try a beach or water start, use the power in the sail to pull you onto the board.
The main thing here is not to push against the board as you do so. That will turn the board downwind and give you too much power in the sail.
Water starting is counter intuitive, in that you've got to push up on the sail and pull in with the foot.
Unlike a lot of people I start with my back foot in the rear strap, that way I have good control of the board and can keep it across the wind without it wanting to roll over. If the wind is light then I have to quickly take my foot out of the strap and move it forward.
So here's a possibility of using the board you've got, it's not the preferred method of learning for most people, because there's no instant reward, it's hard work, and you could look like a fool as you crash and burn. But for somebody young and fit and keen, with reasonable winds it should be possible. And in some cases will get you windsurfing properly, faster than the uphaul method.
But as others have said, a much wider board will be easier, and you can start sailing almost immediately, in light winds with a small sail.
But you have to watch out here, you don't learn bad habits!
The art of good windsurfing is to let the sail do the work, learning to waterstart first teaches you that.
With small gear in light winds, you can overpower the sail, as you progress to bigger sails and stronger winds, you have to unlearn your bad habits.